I have my third copper IUD. I had the first fitted before children as I did not get on with hormonal methods, had the second after my eldest was born and have recently had the third fitted after giving birth to my second child in December. I absolutely love it and would not consider any other method for me. It can make your periods heavier for the first few months, I noticed this with the first IUD but not the one I had fitted after my son (though breastfeeding may have helped keep my periods light). My periods haven't returned yet after the birth so can't comment this time.
I don't have any side effects from it, can't feel it and love the fact I don't need to think about contraception for 10 years!! Happy to answer any questions you might have